Promega Corporation has announced the introduction of a novel cytotoxicity assay that can be used on cell cultures for up to 72 hours, with flexibility for kinetic analysis to determine the onset of cytotoxicity. The CellTox™ Green Cytotoxicity Assay uses an asymmetric cyanine dye as a fluorescent marker that is impermeable to live cells but strongly binds DNA from dead cells, providing a signal that is directly proportional to cytotoxicity.

The CellTox™ Green dye is photostable and non-toxic to mammalian cells, allowing multiple reads over an extended exposure period without compromising cytotoxicity data. Other similar dyes have limited applications due to photo-instability and cytotoxicity to mammalian cells. Also, enzymatic activity biomarker assays that measure cytotoxicity, such as LDH release, have a short biomarker half-life and can result in the underestimation of cytotoxicity if used in extended exposure protocols.

The CellTox Green dye is easily multiplexed with luminescent or other fluorescent cell-based assays with an add-mix-measure protocol to provide more informative data per well. The assay reagent is also easily automated and scalable for use in 96-well to 1536-well formats. This assay is ideal for determining the cytotoxic effects of various treatments on cells in culture following long-term exposure.